Light string is a popular decoration for various venues and occasions, especially during holidays. The structure of light string mainly includes a light head and a light plug, commonly called lampholder and lampbase, respectively. In addition to lampholder and lampbase, the structure also includes LED and wires. When assembled, LED is placed in the lampbase, with the metal leads of the LED extending to outside of the shell of the lampbase and bended towards two opposite sides. The wires are connected to a copper plate terminal. The copper plate terminal and the wires are placed inside the lampholder and fastened. Finally, the lampbase is plugged into the lampholder to accomplish the electrical connection of the metal leads of the LED and the copper plate terminal of the wires. The above structure reveals the assembly process is a complicated sequence of manual operations, which is economically disadvantaged as the labor cost increases.
Another type of LED light string is to place an insulation element between the two metal leads of LED. The outer layer is then sheathed in a thermo-shrunk structure to fasten the LED. This structure requires a heating step during the packaging process to shrink the thermo-shrunk sheath. The high temperature may damage the LED. Some other types even require the injection of insulative glue for water-proof. The expensive material and the complicated process are prohibitive in terms of market competition.